Aminoanthraquinones are well known for use as dyes and coloring agents for oils, drugs, cosmetic products, waxes, and detergents. N,N′-dialkyleneoxy-substituted 1,4-diaminoanthraquinones are usually blue in shade, generally more brilliant than many other blue chromophores, and have good desirable stability properties, especially toward high alkaline environments, heat, and light. This invention relates to a colorant containing compounds having general formula (I):
wherein A1 and A2 are, independently of each other, polyethyleneoxy-, polypropyleneoxy-, or polyethyleneoxy-/polypropyleneoxy-copolymers;wherein the number of repeating polyethyleneoxy-, and/or polypropyleneoxy- units is less than or equal to 25; orwherein A1 and A2 are, independently of each other, —CH2CH2CH2M[(CH2CH2O)x]y—;wherein M can be either O or N and x=1-5, and if M is O, then y=1 and if M is N then y=2; andwherein R1 and R2 represent the terminal group of the polyalkyleneoxy chain and are, independently of each other, selected from the group consisting of OH, NH2, and C1-C8 alkoxy groups.
The colorant of the present invention contains very low levels of impurities, which are generated during the process to make the colorant. One impurity present in an amount that is less than about 1.0% by weight is a violet impurity. This impurity is represented by general formula (II):

wherein A1 and R1 are as defined above in general formula (I).
Yet another impurity present in the colorant composition in an amount that is less than about 1.0% by weight is a water and methanol insoluble black material.
N,N′-dialiphatic-substituted 1,4-diaminoanthraquinone colorants are generally synthesized from 1,4-dihydroxyanthraquinone (i.e. quinizarin) or 2,3-dihydro-9,10-dihydroxy-1,4-anthracenedione (i.e. leucoquinizarin) or a mixture of these two compounds with suitable amines. For example, U.S. Pat. No. 5,756,844 to Baxter et al. discloses a process for producing an aminoanthraquinone dye concentrate wherein quinizarin and/or its leuco derivative is allowed to react with a mixture of three or more aliphatic amines, and wherein the reaction is carried out in the presence of an organic solvent such as glycol and/or a glycol ether (like dipropylene glycol monomethyl ether). U.S. Pat. No. 6,447,591 to Titterington et al. discloses a process for preparing waxy substituted anthraquinone compounds from a mixture of leucoquinizarin and quinizarin. U.S. Pat. No. 3,164,449 to Buxbaum and U.S. Pat. No. 3,597,254 to Graser et al. disclose 1,4-dialkylamino-substituted anthraquinone colorants and mixtures as gasoline colorants.
There are several disadvantages to making anthraquinone colorants according to these methods. For example, several of these patents disclose that organic solvents and catalysts may be utilized for the preparation of colorants. The use of organic solvents, which are generally expensive and not environmentally friendly, usually results in the need for purification of the colorant after synthesis in order to remove the solvents. Additionally, most of the anthraquinone colorants mentioned in these patents are relatively low molecular weight molecules, and they are generally solids at room temperature. Thus, the majority of the dyes disclosed in these patents are not water soluble at room temperature, are not water miscible at ambient conditions, and are not water fugitive (i.e. non-staining).
Other reaction routes also can be used to make the N,N′-dialkyleneoxy-substituted 1,4-diaminoanthraquinone colorants described in the present invention. For example, 1,4-dihaloanthraquinone compounds may be treated with suitable amines and catalysts (such as, for example, copper chloride) to make 1,4-dialiphatic aminoanthraquinone colorants, as described in German Patent No. 125,698. The 1,4-disubstituted aminoanthraquinone compounds may also be made from 1,4-diaminoanthraquinones by reacting with organic halides, as described in German Patent No. 172,464. Additionally, 1,4-ditosyloxy anthraquinone may be used to make both symmetrical and asymmetrical 1,4-diaminoanthraquinone colorants, as described in U.S. Pat. No. 4,746,461 to Zielske. However, many of the raw materials necessary for these processes are generally not readily available. Additionally, many of these processes are not economical and also are not environmentally friendly due to the chemical waste produced.
Other anthraquinone colorants, such as 1,4-disubstituted aliphatic aminoanthraquinones, are disclosed in U.S. Pat. No. 4,846,846 to Rekers et al. wherein anthraquinones were prepared from a mixture of quinizarin, leucoquinizarin, and amine in water followed by various purification procedures. The preferred amines are sec-alkyl primary amines with reactive groups, such as —OH, —NH2, or —SH, on the end of the molecules. These anthraquinone colorants are used to color polyurethane resins, particularly foams. U.S. Pat. No. 4,137,243 to Farmer discloses polymeric anthraquinone colorants with terminal amino groups from leucoquinizarin and polymeric diamines. The leucoquinizarin can be generated in-situ by reduction of quinizarin with sodium hydrosulfite. The polymeric aminoanthraquinone colorants, prepared according to the above patent processes, also contain high levels of impurities such that further purification is needed to obtain higher purity anthraquinone colorants. Purification of low melting or liquid water-soluble anthraquinone colorants usually involves time consuming extraction and washing procedures that often require organic solvents, which generally are not environmentally friendly. Additionally, these solvents are typically not suitable for use in many consumer product applications and complete removal is required. The organic solvents are often expensive and generate additional waste during production of the anthraquinone colorants. Furthermore, some of the impurities in these anthraquinone colorants are often difficult to filter and generally cause dull color, shade shift, and staining.
Thus, there is a need for a colorant which may be used in various consumer products (such as liquid and solid laundry detergents and liquid fabric softeners) that has low levels of impurities, that is non-staining, that is made without the use of organic solvents, and that is made without the use of expensive and time-consuming purification and filtration steps. Accordingly, one object of this invention is to provide an N,N′-dialkyleneoxy-substituted 1,4-diaminoanthraquinone colorant with reduced amounts of impurities. Another object of this invention is to provide methods to make such anthraquinone colorants without the use of solvents. A further object of this invention is to use these inventive colorants for coloration of consumer products, such as liquid and solid laundry detergents and liquid fabric softeners.